#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
int main()
{
	int a, b, c;
	scanf("%d %d %d", &a, &b, &c);

	if (a + b > c && a + c > b && b + c > a)
		printf("YES");
	else
		printf("NO");
	return 0;
}